Module location 

Unit-test location/naming check for Python sources (issue #15).

The convention (README “Location & Naming”; internals/python/testing.md): a Python source file foo.py is unit-tested by a colocated foo_test.py. missing_unit_tests walks a directory tree and returns every source file that has no such sibling — an “orphan”. Files that are themselves tests (*_test.py) are what the check looks for, never subjects, and the package marker (__init__.py) is exempt.

Functions

missing_unit_tests

Walk root recursively and return every Python source file that has no colocated <stem>_test.py, sorted for deterministic output.